I’m still of the opinion that physically removing soil from non porous surfaces is pretty close to 100% of the solution, but a couple of observations:

– Grout is porous and irregular – hence hard to remove 100% of odor causing soil, hence enzymes are part of the solution.

– Even on a hard non porous surface like porcelain, there can be pits and irregularities that trap soil, hence, again, enzymes left behind from a cleanser would help.

The same caveats with all applications of enzymes apply – you need to leave enough moisture on the surface for the enzymes to activate and “dwell” long enough to do their work. The article sidesteps this a little bit with it’s recommendation of repeated use.

– You’re going to do better with a neutral surface – if you are putting acids (or alkaline all purpose cleaners) on the fixtures you might want a clear rinse or two to get rid of any residual ph.